Since the appearance of an object in a scene depends greatly upon the illuminant colour, the recovery of the light power spectrum finds applications in recognition, surveillance and visual tracking. Despite its importance, the recovery and identification of illuminant colours in the scene has proven to be a difficult task in uncontrolled real world imagery. This is mainly due to the fact that the recovery of the region-wise illuminant from a single image is an under-constrained problem. As a result, existing colour constancy algorithms, such as the grey-world, grey-edge and shades of grey method, assume uniform illumination or an achromatic scene. In other solutions, the colour constancy problem is tackled assuming that the statistical mean of the spatial derivative across the image is independent of the chromaticity or it is assumed the reflectance distribution to be Gaussian.
In natural everyday scenes, however, these assumptions can be too restrictive. This arises because in practice, real-world imagery can comprise shadows, highlights and albedo variations arising from several light sources.
Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present disclosure as it existed before the priority date of each claim of this application.
Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.